The following discussion of the prior art is provided to place the invention in an appropriate technical context and enable the advantages of it to be more fully understood. It should be appreciated, however, that any discussion of the prior art throughout the specification should not be considered as an express or implied admission that such prior art is widely known or forms part of common general knowledge in the field.
Fabric conditioning compositions can be added in the rinse cycle of the laundering process to soften fabrics and to impart them nice smell. Conventionally, fabric conditioning systems are based on quaternary ammonium compounds, also named as quats, notably cetrimonium chloride, behentrimonium chloride, N,N-bis(stearoyl-oxy-ethyl) N,N-dimethyl ammonium chloride, N,N bis(tallowoyl-oxy-ethyl) N,N-dimethyl ammonium chloride, N,N bis(stearoyl-oxy-ethyl) N-(2-hydroxyethyl) N-methyl ammonium methylsulfate or 1,2-di(stearoyl-oxy)-3-trimethyl ammoniumpropane chloride. Advantageously, ester quats can be used as fabric conditioning actives. Ester quats are bio-degradable and exhibit lower eco toxicity, and therefore, there is a trend in the industry to use ester quats as the fabric conditioning actives.
It is highly desirable that the fabric conditioning compositions can have good conditioning performance combined with excellent stability. Fabric conditioning compositions with poor stability may become unpourable and have inadequate dispensing and dissolving characteristics in rinse water. This is in particular a problem when the fabric conditioning actives are present at high concentrations which may be required for achieving good conditioning performance. One option to solve this problem is to lower the dosage level of the quats in the composition by replacing some of the quats with a cationic polymer, such as a cationic polysaccharide. The art teaches that addition of cationic polymers to fabric conditioning compositions has a variety of benefits. U.S. Pat. No. 6,492,322, Megan et al., discloses fabric softening compositions comprising biodegradable di-ester softening compounds and cationic polymers including polysaccharides, such as gums, starches and certain cationic synthetic polymers.
However, replacing the quats with a cationic polysaccharide in the fabric conditioning compositions will lead to another problem. More specifically, the quats and the cationic polysaccharide, when combined, tend to separate. As a result, compositions comprising such components are no longer homogeneous and segregate into different phases. This is in particular an issue when these compounds are combined in an aqueous composition. This may pose problems to the user upon usage or may affect retailers when placing products on the shelves, without mentioning any associated loss of performance for the softening products.
Thus, it remains a challenge to provide a fabric conditioning composition having excellent softening performance combined with good stability. It remains a challenge to provide a fabric conditioning composition which can have long shelf life and which can remain stable and homogenous for extended time. In particular, it remains a challenge to provide a fabric conditioning composition with good stability without jeopardizing the dispersibility of the composition in aqueous solutions.